Rivet set



Patented May 11,1926.

- UNITED STATES WILLIAM S. IBIDLlE, 0F CLEVELAND, OHIO, ASSIGNOR TO THES. BIDLE COMPANY,

PATENT: orrics or CLEVELAND, OHIO, A: CORPORATION or o'rrro; a I

RIVET sn'r.

Application filed November 7, 1925. Serial No. 67,588.

My invention relates to an improvementin rivet sets, and the primaryobject of my 1nvention is to provide a rivet set which is view of myimproved rivet set made in two separableparts, and. Fig.2 is aside viewof a common type ofrivet set, of the same size, the two viewspermittingcomparison of the shape of their respective heads and shanks.

Fig. 3 is a side elevation of the main part of the rivet setrwithou'tits split ring, and" Fig. t'is a horizontal cross, section of the headand split ring, on line H of Fig. 1.

' The common type of rivet set A, shownin Fig. 2, is made in one pieceand comprises a grooved head a having a straight integral shank ajoined'to the'head with a short or abruptly curved fillet a". .Thegeneral contour and size of such rivet sets permits them to be usedefiectively withpneumatic tools, the shank fittingloosely within aworking bore where it may be engaged repeatedly by a piston or hammerand the head being.

grooved to permit it to be held by a retaining clip or'other device sothat the rivet set may not be ejected accidentally when not held againstthe work. In recoiling, the shoulder or fillet portion a strikesthe endof the pneumatic tool and it is usually at this juncture a that therivet set develops fatigue and fractures.

.My improved rivet set comprises a round straight shank 2 of the samediameter and length as the shank in the old type described so'that itmaybe removably fitted Within any standard pneumatic riveting tool inwhich a reciprocable piston or hammer is, employed to repeatedly strikethe chain fered end portion 3 of the shank. An enlarged upsetting orriveting'head 4 forms an integral part of shank 2, the material in-,

volved in this head being the same in length as in the old type andconsisting of all of that portion beginning with the riveting end 5having riveting cavity 6 and including the tapering curved connectingportion 7 of lesser diameter which joins with and terminates at the base.end of straight shank 2. Thus the rounded riveting: part 5 of the headis relatively the largest integralpart of the rivetset, beingcorrespondingly as wide vertically as annular enlargement 5 in the oldtype of rivet set'A shown in Fig. 2 but made slightly larger in diameterto provide 'a flat annular seat or shoulder 8v at right angles to thestraight side of a reduced section 9 of heme, Reduced part ,9 is ofslightly less diameter than the grooved part 9 of the old'typeof rivethead a which comprises a narrow annular rib or enlargement a at theabrupt juncture with shank a.

device but it islocated much" nearer to the rounded riveting end '5 toprovide a narrower reduced part or groove 9- compared with groovedpart9' in the old head a.' Thence head 4: tapersupwardly on along curve orradius 11 to produce a gradual decrease in seats the'fiat end 120i asplit ring 13 made oi hardened spring steel. In that c0nnection, Ilfindthat an abrupt change in cross section is permissable in head eitselfprovid ing it is located relatively near the upsetting end where thestock in the head and not the stock in the shank is involved. Thus itshould be noted that shoulder 8 is formed by slightly enlarging the headand that the annular reduced part 9 is considerably larger in diameterthan shank 2' and also larger than riveting cavity 6 in end 5. Ring 13maybe made of a cheaper grade of material.

than head 4 but it is hardened and tempered to prevent it from upsettingunder recoil movements of the hammer.

ment 10 and fits snugly within the grooved part 9 inhead 4E, and anannular grooyelf) formed externally of the ring provides limiting stopshoulders 16' for the spring clip or other holding device (not shown)but customarily employed to grip and hold Ring is "tormed internally at1ts lower end with, an

annular rib 14 which springs over enlarge,

A'similar narrow annular rib'or enlargement 10 forms part. of head 4 inmy more, the flat seat 8 for the ring resists squarely, the recoil, andprevents any spreading or wedging effect from being transmitted to thesplit ring.

Head 4 is subjected to great strain and Wear and obviously this partwith its integral shank must in time be replaced, but

split ring 13 being made of spring steel and heat treated and temperedseparately from the main member may be removed from a worn riveting headand replaced on a new one by the aid of suitable tools. However, ariveting head and shankconstructed according to my invention willwithstand severe usage and outlast all other types of rivet sets knownto me and in general use,

the device having been particularly designed to resist exceptionallyhigh fatigue stresses.

In that connection it should be understood that fatigue tests havedemonstrated that sudden changes of cross-section should be avoided atcritical places or especially important junctures as abrupt changes ofoutline greatly lower the resistance of the specimen to repeated stress.High stress concentration is produced by sharp varia tions ofcross-sections with fillets of small radius and in the case of hard andbrittle steels the action of stress reversal becomes of more importancethan with softer steels. Rivet sets must be hard in order to stand upunder the repeated blows of the hammer and to do the work required ofthem, and this demands that they be left in the martensitie conditionafter hardening. Martensite is however brittle compared to sorbite whichpresents the best structure to resist fatigue, and so the use of a headof gradually diminishing cross section and a gradual merger of this headwith a straight shank becomes of especial importance in a rivet setwhich must be left in a martensitic condition. For diverse reasons ithappens that rivet sets for pneumatic hammers in general usemust be madewith heads of considerably larger diameter than the shank, so that inhardening a piece of steel for a rivet set which has a large headsection adjacent to a very much smaller one, such as a round shankconnected with a short radius fillet, as shown in Fig, 2, there areinternal stresses set up in the shank at the junction on quenching,and'these' stresses are not completely removed by subsequent tempering.These internal stresses help to form a nucleus for hasthe shank.

tening the progressive failure of the finished article when it issubjected to repeated stress as in a rivet set. would be best to havethe steel of uniformly fine-grain throughout at the junction be tweenthe head and shank as fine-grained structures have endurance propertiessuperior to those of coarse-grained. In the case of an abrupt change ofsection in a rivet which causes the set to failat this point.

long before the riveting .end or'cavity has been worn out in headingrivets, etc. A rivet set constructed according to my invention providesa gradually diminishing amount of metal between the upsetting end shankthereby avoiding fatigue stresses at a critical place in the tool, andWhere an abrupt change in cross-section is'necessary or desirable, suchas at grooved part 9* to produce flatseat 8, it should be placed nearthe point of application of the force at the forward part of the headWhere the area or stock is from 80% to 100% greater than that of theround shank itself and not subject to the concentration of stress asatl/Vhat I claim, is: I

l. A rivet set, comprising a riveting head having an annular groove andseat relatively near the upsetting end thereof and formed with anintegral round shank of lesser di ameter than the grooved part of saidhead, said head gradually diminishing in diameter from said grooved partto said shank, and a separate recoil-resisting ring atfixed to thegrooved part'of said head adapted to bear against said seat.

2. A rivet set, comprising a head and an integral shank of reduceddiameter, said head having an external groove intermediate its outer endand its juncture'with said shank, and a recoil-resisting ring having aninternal rib confined within. said groove and formed with spaced annularshoulders externally adapted to confine a retaining member.

3. A rivet set having a round head and an integral shank of reduceddiameter, said head having an external groove annularly thereof andtapering gradully from said groove to said shank, and a split recoil-resisting ring seated within said groove in de-' tachable connection withsaid head,

' 4:, A rivet set having a round head and Theoretically it 3 of the headand the beginning of the straight an integral shank of reduced diameter,said head having a fiat shoulder annularlythereof at right angles to theaxis of the head and formed with a small annular enlargement adjacentsaid shoulder, said head tapering gradually from said enlargement tosaid shank, and a split ring having a flat end largement and formed withan annular 1 groove externally. a V In. testimony whereof I affix mysignature.

lVILLIAM S. BIDLE.

